Problem: Compute: $\sqrt{8\times 18\times 20\times 5}$.
Explanation: Group factors under the radical to make perfect squares: \begin{align*} \sqrt{8\cdot18\cdot20\cdot5}&=\sqrt{(4\cdot2)\cdot18\cdot20\cdot5} \\ &=\sqrt{(4)(2\cdot18)(20\cdot5)} \\ &=\sqrt{(4)(36)(100)} \\ &=(2)(6)(10) \\ &=\boxed{120}. \end{align*}